Treatment of carpal tunnel syndrome by injection of the flexor retinaculum

ABSTRACT

An apparatus and method for identifying the flexor retinaculum of the carpal tunnel, injecting an effective amount of an agent into at least a portion of flexor retinaculum or tissue adjacent thereto, wherein the agent is configured to weaken the flexor retinaculum. The system may further include means for increasing the tensile stress in the flexor retinaculum post-injection using hand exercises, thereby weakening its structural integrity and decreasing the pressure within the carpal tunnel that impairs median nerve function.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. provisional patentapplication Ser. No. 61/163,165 filed on Mar. 25, 2009, incorporatedherein by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention pertains generally to treatment of carpal tunnelsyndrome, and more particularly to both a method and apparatus fortreatment by injection of a biological substance into the flexorretinaculum.

2. Description of Related Art

The carpal tunnel is an area in the hand adjacent the wrist which isformed by an arch of the eight wrist bones, spanned on its palmarsurface by the flexor retinaculum. Functionally, the flexor retinaculumacts as a pulley. Passing through the carpal tunnel are nine flexortendons with their synovial membranes, four lumbrical muscles, andmedian nerve. Without the flexor retinaculum, the flexor tendons tend tobowstring, losing their ability to preserve their appropriate momentarms, and resulting in a loss in both strength and dexterity to thewrist and hand that the carpal tunnel tendons help control.

Carpal tunnel syndrome (CTS) is a disease that refers to numerousclinical signs and symptoms resulting from an increase in pressure onthe median nerve inside the carpal tunnel. The increased pressurecompresses the median nerve, compromising its blood flow, resulting inthe pain, numbness, and tingling characteristic of this disease. Atpresent, it is the most widespread occupational health hazard in theindustrial world. Billions of dollars are consumed each year in lostworking time and in the diagnosis and treatment of this syndrome.

Intracarpal tunnel pressure is dynamic and influenced by numerousfactors. Many of these factors have been studied previously, includingdisease, injury wrist position hand use compliance of the flexorretinaculum lumbrical muscles, externally applied force, and fingerposition. Not only does intracarpal tunnel pressure vary in response tothese factors, but pressure dynamics also are determined by geometry ofthe carpal tunnel. Because of both the complex geometry and interactionamong these factors, accurate measurement of intracarpal tunnel pressureremains difficult. In addition, pressure measurement is dependant on thetype of measurement device used and whether introduction of themeasurement device itself alters the pressure.

Active hand use produces the greatest range of pressures within thecarpal tunnel. Most studies measuring intracarpal tunnel pressure duringactive hand use included patients with carpal tunnel syndrome (CTS).However, none of these studies quantified the hand use during pressuremeasurement. Because intracarpal tunnel pressure also is a function oflocation within the tunnel where pressure measurement is obtained, anycharacterization of the dynamics of intracarpal tunnel pressure shouldinclude a profile of pressure within the carpal canal. While others haveidentified the pressure profile that exists from proximal-to-distalwithin the carpal canal, only one of these included pressuremeasurements during active hand use. However, quantification of hand usewas not reported.

Although the underlying cause of CTS is unknown, the treatment for CTSis well established. Non-operative treatments, including splinting,anti-inflammatory medications, and cortisone injections into the carpaltunnel, are often used initially to provide temporary relief of thesymptoms. When non-operative treatments fail, the most effectivetreatment of CTS is surgical division of the flexor retinaculum.Surgical division of the flexor retinaculum causes a decrease in thepressure in the carpal tunnel allowing the return of normal blood flowto the median nerve, relieving the signs and symptoms of CTS. Whilevarious techniques exist for releasing the flexor retinaculum, the twomost commonly used are open and endoscopic.

During an open release, a longitudinal incision is made through the skinin the palm of the hand and carried down through the subcutaneous fat,palmar fascia, palmaris brevis muscle, and finally through the flexorretinaculum. Once the flexor retinaculum is released, the skin issutured and the wrist is frequently splinted until the wound heals. Atypical surgery requires approximately 15 to 30 minutes and is performedas an outpatient procedure.

For an endoscopic release, various devices exist to perform incision ofthe flexor retinaculum. One device comprises a video endoscope and ahand piece that holds a disposable blade assembly. The device isinserted through a limited incision located in a wrist flexion crease.While viewing the deep side of the flexor retinaculum through a windowlocated at the tip of the device, the blade is elevated to make thelongitudinal incision while the device is withdrawn from the carpaltunnel. Next, the device is used to inspect the completeness of theincision through the flexor retinaculum and perform additional cuttingif necessary. Once complete incision of the flexor retinaculum isachieved, the entry wound is sutured. The endoscopic release isperformed as an outpatient procedure and requires approximately the sameamount of time to perform as the open release.

Although complete surgical division of the flexor retinaculum ispromoted as the standard of care in patients with CTS, there are anumber of potential disadvantages associated with it, including:

(a) The arch formed by the carpal bones may be altered, affecting thefunctional biomechanics of the hand.

(b) The pulley effect created by the flexor retinaculum may becompromised and/or lost, allowing the digital flexor tendons and/ormedian nerve to sublux palmarwardly between the cut edges of the flexorretinaculum. Power grip and pinch are compromised until the flexorretinaculum heals adequately to re-establish the carpal tunnel as acompetent pulley for the nine digital flexor tendons.

(c) Exposure of the cut edges of the flexor retinaculum permit scartissue necessary for its healing in the lengthened position to be moreabundant and therefore potentially creating greater post-operativemorbidity, pain, and weakness.

(d) The length of time required for a patient to return to both theiractivities of daily living and work is affected by the trauma associatedwith a complete ligament division.

(e) The surgical techniques used require the expense of an operatingroom procedure rather than an office or clinic procedure.

(f) Following complete division of the flexor retinaculum, portions ofthe origins of the thenar and hypothenar muscle groups are unstable,causing pain and weakness of pinch and grip during the healing of theflexor retinaculum.

To avoid the potential disadvantages associated with current surgicaltechniques, an object of the present invention a method and apparatusthat weakens the structural integrity of the flexor retinaculum withoutusing a surgical incision or surgically dividing portions or all of theflexor retinaculum. At least some of these objectives will be met in thefollowing description.

BRIEF SUMMARY OF INVENTION

The present invention includes system and method to alter the stiffnessof the flexor retinaculum so that it becomes more compliant, therebycausing the circumference of the carpal tunnel to expand and thusdecrease the pressure on the contents of the carpal tunnel; similar towhat occurs after surgical division of the flexor retinaculum. Thisallows the pressure within the carpal tunnel to return to an acceptablelevel, relieving the symptoms of CTS without a surgical operation.

According to an aspect of the invention, an apparatus and method isprovided for identifying the flexor retinaculum of the carpal tunnel,injecting an effective amount of a drug either into any part of oradjacent to the flexor retinaculum (i.e. close enough to the flexorretinaculum so that the drug is effective), and increasing the tensilestress transmitted into the flexor retinaculum post-injection using handexercises, thereby weakening its structural integrity and decreasing thepressure within the carpal tunnel that impairs median nerve function. Inone embodiment, the apparatus comprises: (a) a drug with the ability toweaken the structural integrity of collagen; (b) an imaging detector foridentifying the flexor retinaculum; (c) a detector frame configured tobe coupled to the palm of the hand that both holds and positions thedetector; (d) an injection needle with syringe for injecting the drug;and (e) a needle guide either attached to or integral with the imagingdetector that holds, positions, and guides the injection needle.

Any drug that weakens the structural integrity of collagen may be used.In a preferred embodiment, collagenase may be used. Collagenase is anenzyme that has the affect of digesting collagen by breaking down thepeptide bonds in the collagen protein.

The flexor retinaculum of the carpal tunnel comprises collagen fibersthat are susceptible to breakdown by collagenase. Thus, the methods andsystems of the present invention offer significant improvements over thecurrent surgical methods by injecting collagenase either into any partof, or tissue adjacent to, the flexor retinaculum of the carpal tunnel,weakening the structural integrity of the collagen fibers, increasingthe tensile stress in the flexor retinaculum, and causing the ligamentto increase in length, thereby decreasing pressure on the median nerveand relieving the symptoms of CTS.

The present invention may include a combination of collagenase with aliquid carrier in an effective concentration for injection into or nearthe flexor retinaculum to weaken the structural integrity of collagen.

The “structural integrity” of collagen is herein defined as the abilityof collagen to withstand tensile load. Once the structural integrity ofcollagen is weakened by collagenase, the threshold for tensile loadingis lowered and the collagen fibers are no longer able to withstand thetensile loads that they could previous to the injection. Once tensileloads exceeding this lower threshold are applied to the collagen fibers,individual fibers fail structurally as a result of the broken bonds inthe collagen protein. Initially, failure of the collagen fibers occurson a microscopic level, progressing to complete failure of the collagenstructure as the tensile load increases.

Direct injection of a drug into a part of or adjacent to the flexorretinaculum might be possible using only visual and palpation methods bya skilled physician knowledgeable of the anatomy of the hand. However,because the flexor retinaculum is deep to the palmar surface of the handand neither visible nor palpable, an imaging means is desirable. Inaddition, to ensure that the drug dosage required to achieve the desiredeffect is accurately delivered at either a specific location or multiplelocations either in or directly adjacent the flexor retinaculum, animaging means is required for identifying the flexor retinaculum.

The imaging means can be any standard noninvasive imaging detectortypically used for guiding injection needles. In the preferredembodiment, the imaging detector is an ultrasound transducer. Anystandard commercially available ultrasound transducer with both hardwareand software capabilities to produce high quality images of the anatomyof the wrist and hand can be used. While holding the imaging detectoragainst the palmar skin and adjusting its position, the physician canobserve on a display monitor acceptable images of both the flexorretinaculum and vital anatomic features that require avoidance duringinjection, including the median nerve, ulnar nerve, ulnar artery, andflexor tendons to the fingers. In addition, ultrasound can be used toidentify the hook of the hamate, which is the anatomic attachment of thestiffest portion of the flexor retinaculum. It is at this location wherethe median nerve is the most compressed in the carpal tunnel. From theimages, the flexor retinaculum can be both visually identified and itspalmar-to-dorsal depth computed relative to a fixed reference position.In addition, having real-time images of the injection needle withrespect to the anatomy of the carpal tunnel enables more accurate andrepeatable injections of a drug at specific locations.

While holding and positioning the imaging detector can be performedmanually by the physician, it is beneficial to have a detector framethat aids in this task. In the preferred embodiment, the detector frameis coupled to the patients hand. The detector frame both holds theimaging detector and provides both translational and rotationalpositioning of the imaging detector on the palm of the patient's hand.Use of a detector frame enables more freedom of the physician's hands,ensures stable images of the desired anatomy, and provides a stablereference frame from which an injection needle can be guided.

With the flexor retinaculum both identified and its depth known relativeto the palmar skin, an injection needle can be guided to it. Anystandard commercially available hypodermic needle of suitable length anddiameter and syringe (or equivalent means for containing the drug to beinjected) of appropriate sizes can be used to dispense an effectiveamount (dose) of drug. Using either visual guidance provided by theultrasonic images or depth information computed from the ultrasound, thetip of the injection needle can be inserted either into a specificsegment of or adjacent to the flexor retinaculum.

While holding, positioning, and guiding the injection needle can beperformed manually by the physician, it is beneficial to use a needleguide that aids in this task. In the preferred embodiment, a needleguide attaches to the imaging detector and holds the injection needle,positions it at both the desired angle and location for entry into theskin, and guides the needle, as it is advanced by the physician, along atrajectory that ensures insertion of the tip of the needle at thedesired location either into or adjacent the flexor retinaculum. Once atthe desired location, the physician can dispense an effective dosage ofthe drug.

After deposition of the drug either into a part of or adjacent to theflexor retinaculum, it may be necessary, once the structural integrityof the collagen fibers have weakened, for the patient to activelyincrease the magnitude of tensile stress in the flexor retinaculum. Theresulting increase in tensile stress in the weakened collagen fiberswill cause them to either abruptly fail or increase in anatomic lengthover time. To provide the necessary increase in tensile stress in theweakened collagen fibers, the physician may prescribe a hand exerciseroutine.

Accordingly, an aspect of the present invention is a method for treatinga patient with carpal tunnel syndrome, comprising: identifying alocation of the patient's flexor retinaculum suitable for treatment; andinjecting an agent into said location of the flexor retinaculum in oneor more doses sufficient to weaken the structural integrity of theflexor retinaculum.

In one embodiment, the flexor retinaculum includes the transverse carpalligament and/or its attachment to the bones.

In another embodiment, the agent comprises: one or more doses ofcollagenase, a corticosteroid, or both.

In a further embodiment, identifying a suitable treatment location ofthe patient's flexor retinaculum comprises: positioning an imagingdetector adjacent a region of the patient's hand; the region beingassociated with the flexor retinaculum, and generating an image of thepatient's hand. The imaging detector may comprise ultrasound imaging,X-ray imaging, Magnetic Resonance Imaging, or the like.

In one mode of the current embodiment, generating an image comprisespositioning an ultrasound transducer adjacent the patient's hand andgenerating an ultrasound image.

In another embodiment, the method further includes increasing thetensile stress in the flexor retinaculum subsequent to injecting saidagent. The increase in tensile stress may be generated by pressurewithin the carpal tunnel, said pressure generated by one or more of thefollowing: having the patient use one or more digits of the hand, havingthe patient grip the hand around an object; flexing one or more fingersinto the palm of the hand and having the patient pinch a thumb and oneor more fingers of the hand together. The object may comprise adynamometer, and be pressed into the palm or heel of the patient's hand.

In yet another embodiment, the method includes measuring pressure withinthe carpal tunnel

In addition to the injection of an agent, the method may include cuttingthe flexor retinaculum with a blade.

In one embodiment, identifying a suitable treatment location of thepatient's flexor retinaculum further comprises computing thepalmar-to-dorsal depth from the palm of the hand to the flexorretinaculum; wherein the agent is injected via a needle at saidcomputed-to-palmer-to-dorsal depth along an axis substantially parallelto an imaging surface of the detector, or a longitudinal axis of theflexor retinaculum.

In another embodiment, the agent is delivered at a central portion ofthe flexor retinaculum.

In a further embodiment, the method may include inserting a guide tubeinto the hand adjacent the flexor retinaculum; and accessing the flexorretinaculum at the distal end of the guide tube. In the current mode,the method may include advancing a pressure sensor within said guidetube to said treatment location, and measuring the pressure at saidlocation. In addition, the method may include advancing a cutting probewithin said guide tube to said treatment location; and cutting tissueassociated with the flexor retinaculum.

Another aspect is a system for treating a patient with carpal tunnelsyndrome, comprising: a needle guide; an injection needle; the needleguide comprising a guide hole configured for receiving the injectionneedle; and an agent configured for delivery within said injectionneedle to a tissue region associated with the flexor retinaculum of thepatient; wherein said agent is configured to weaken the structuralintegrity of the flexor retinaculum.

In one embodiment, the system includes a clamp coupled to the needleguide; wherein the clamp comprises a reference surface for positioningat a palm of the patient's hand; wherein the needle guide is slideablycoupled to the clamp such that the needle guide may be adjusted withrespect to the reference surface. In a preferred mode, the longitudinalaxis of the guide hole is substantially parallel to the referencesurface.

In another mode of the current embodiment, the system comprises animaging device configured for imaging the carpal tunnel duringinjection; wherein the clamp is configured to house the imaging device.The imaging device may be pivotably coupled to the clamp to allow fortransverse and longitudinal images of the carpal tunnel to be obtained.

In another mode, the imaging device comprises an imaging surface;wherein the imaging surface is substantially parallel to thelongitudinal axis of the guide hole of the needle guide. The needleguide may be configured to be adjusted in a palmar-dorsal directionwhile the guide hole remains substantially parallel to the imagingsurface. The clamp and needle guide may comprise an indicator configuredto indicate a depth of needle insertion with respect to the referencesurface.

In another embodiment, the system includes a guide tube disposed withinthe guide hole; the guide tube configured to be inserted into the handadjacent the flexor retinaculum; wherein the guide tube comprises acentral channel sized to accommodate delivery of an instrument to thetissue region. The delivery instrument may comprise a pressure sensorsized to be received within said guide tube to be delivered to thetissue region; wherein the pressure sensor is configured to measuringthe pressure at said location, or a cutting probe sized to be receivedwithin said guide tube to be delivered to the tissue region; and thecutting probe configured to cut tissue associated with the flexorretinaculum.

In another embodiment, a linkage is attached to the clamp; wherein thelinkage is configured to secure to the patients hand; wherein thelinkage comprises a first joint that allows rotation of the clamp withrespect to the hand. The first joint is configured to allow rotation ofthe clamp in a flexion-extension direction with respect to the patient'shand. The linkage may further include a second joint; wherein the secondjoint is configured to allow rotation of the clamp in a radial-ulnardirection with respect to the patient's hand.

In another embodiment, the linkage system provides translational androtational adjustments of the imaging detector and needle/probe guiderelative to the patient's hand. In one mode of the current embodiment,the linkage system establishes a fixed point distal to the imagingdetector about which the longitudinal axis of a contact line between apatient's ring and long fingers always intersects.

Another aspect is an apparatus for treating a patient with carpal tunnelsyndrome, comprising: a needle guide; an injection needle; the needleguide comprising a guide hole configured for receiving the injectionneedle; a clamp coupled to the needle guide; wherein the clamp comprisesa reference surface for positioning at a palm of the patient's hand;wherein the needle guide is slideably coupled to the clamp such that theneedle guide may be adjusted with respect to the reference surface; andan imaging device configured for imaging the carpal tunnel duringinjection; wherein the clamp is configured to house the imaging device.

The apparatus preferably includes an agent configured for deliverywithin said injection needle to a tissue region associated with theflexor retinaculum of the patient; wherein said agent is configured toweaken the structural integrity of the flexor retinaculum. Preferably,the guide hole is substantially parallel to the reference surface.

In one embodiment, the apparatus further comprises a linkage attached tothe clamp; wherein the linkage is configured to secure to the patientshand and has first and second joints that allow rotation of the clampwith respect to the hand; wherein the first joint is configured to allowrotation of the clamp in a flexion-extension direction with respect tothe patient's hand; and wherein the second joint is configured to allowrotation of the clamp in a radial-ulnar direction with respect to thepatient's hand.

Another aspect is an apparatus for treating a patient with carpal tunnelsyndrome, comprising: a base configured to support a patient's forearmand hand; the base comprising a first surface configured to support theforearm and a second surface configured to support the hand; wherein thesecond surface is adjacent to the first surface and disposed at an anglewith the first surface; a pivotable arm coupled to the base; wherein thepivotable arm is configured to support a needle guide; the needle guidecomprising a guide hole configured for receiving the injection needle;and a clamp coupling the pivotable arm and the needle guide; wherein theneedle guide is slideably coupled to the clamp such that the needleguide may be adjusted with respect to the second surface.

In a preferred embodiment, the apparatus includes an agent configuredfor delivery within said injection needle to a tissue region associatedwith the flexor retinaculum of the patient; wherein said agent isconfigured to weaken the structural integrity of the flexor retinaculum.

In another embodiment, the apparatus includes an imaging deviceconfigured for imaging the carpal tunnel during injection, wherein theclamp is configured to house the imaging device.

In yet another embodiment, the guide hole is substantially parallel tothe second surface, and the needle guide is configured to be adjusted ina palmar-dorsal direction while the guide hole remains substantiallyparallel to the second surface. The clamp and needle guide comprise anindicator configured to indicate a depth of needle insertion withrespect to the reference surface. Furthermore, the pivotable arm allowstranslation and rotation of the needle guide with respect to the secondsurface.

Another aspect of the invention is a method for treating a patient withcarpal tunnel syndrome, comprising: injecting a drug into or adjacent tothe flexor retinaculum in one or more doses sufficient to weaken thestructural integrity of the flexor retinaculum: and increasing thetensile stress in the flexor retinaculum. The pressure within the carpaltunnel may also be measured. Additionally, the flexor retinaculum may becut with a blade and using an imaging method to display the flexorretinaculum on a monitor while cutting.

Another aspect of the invention is a percutaneous injection device foruse with a medical imaging detector, comprising: a clamp configured forattachment the imaging detector; a needle guide configured forattachment to the clamp and which is adjustable along an axis that issubstantially parallel to the longitudinal axis of the imaging detector;and an injection needle configured for insertion through the needleguide; the injection needle having a longitudinal axis substantiallyparallel to the imaging surface of the imaging detector when insertedthrough the needle guide.

Another aspect of the invention is a system for treating a patient withcarpal tunnel syndrome, comprising: an imaging detector; a clamp thatcouples to the imaging detector; a guide that attaches to the clamp andis adjustable along an axis that is substantially parallel to thelongitudinal axis of the imaging detector; a probe with a cutting bladewhose long axis is substantially parallel to the imaging surface of theimaging detector when inserted through the guide; and a pressuremeasurement device for measuring pressure within the carpal tunnel.

Another aspect of the invention is a device for a medical imagingdetector, comprising: a clamp configured to attach to the imagingdetector; a probe guide configured to attach to the clamp and which isadjustable along an axis that is substantially parallel to thelongitudinal axis of the imaging detector; a probe with a cutting bladewhose long axis is substantially parallel to the imaging surface of theimaging detector when inserted through the probe guide; and a linkagesystem attached to the clamp that attaches to the patient's hand.

Another aspect of the invention is a system for treating a patient withcarpal tunnel syndrome, comprising: an imaging detector; a guide that isintegral with the imaging detector and is adjustable along an axis thatis substantially parallel to the longitudinal axis of the imagingdetector; and a probe with a cutting blade whose longitudinal axis issubstantially parallel to the imaging surface of the imaging detectorwhen inserted through the guide.

Further aspects of the invention will be brought out in the followingportions of the specification, wherein the detailed description is forthe purpose of fully disclosing preferred embodiments of the inventionwithout placing limitations thereon.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

The invention will be more fully understood by reference to thefollowing drawings which are for illustrative purposes only:

FIG. 1 is a perspective view of an embodiment of an injection apparatusaccording to the present invention, with the imaging detector positionedparallel to the imaged anatomy.

FIG. 2 is a perspective view of an embodiment of an injection apparatusaccording to the present invention with the imaging detector positionedtransverse to the imaged anatomy.

FIG. 3 is a perspective view of an embodiment of an injection apparatusaccording to the present invention similar to that shown in FIG. 1, butwith the injection needle replaced with alternative devices formeasurement and treatment of carpal tunnel syndrome.

FIG. 4 is a perspective view of an embodiment of an injection apparatusaccording to the present invention shown secured to the hand.

FIG. 5 is an anterior-posterior view of the injection apparatus shown inFIG. 4.

FIG. 6 is a side view of an embodiment of an injection apparatusaccording to the present invention similar to that shown in FIG. 4, butwith the injection needle replaced with alternate devices formeasurement and treatment of carpal tunnel syndrome.

FIG. 7 is a perspective view of an embodiment of an injection apparatusaccording to the present invention similar to that shown in FIG. 6, butwith the alternate devices for measurement and treatment of carpaltunnel syndrome shown inserted palmar to the flexor retinaculum.

FIG. 8 is an anterior-posterior view of an embodiment of an injectionapparatus according to the present invention similar to that shown inFIG. 4, but with a detector clamp that enables rotation of the imagingdetector to obtain various image views.

FIG. 9 is a perspective view of an embodiment of an injection apparatusaccording to the present invention shown with the apparatus mountedseparate from the hand.

FIG. 10 is an anterior-posterior view of the injection apparatus shownin FIG. 9.

FIG. 11 is a perspective view of a standard grip dynamometer with dataacquisition and display module.

FIG. 12 is a perspective view of a standard pinch dynamometer with dataacquisition and display module.

FIG. 13 illustrates a hand with indicated measurement locations chosenand standardized based on a DWC-HH measurement.

FIG. 14 illustrates placement of a pressure sensor confirmed usingfluoroscopy.

FIG. 15 illustrates testing for measurements made on a patient's handfor maximum grip force (MGF).

FIG. 16 illustrates testing for measurements made on a patient's handfor maximum pulp pinch force (MPF).

FIG. 17 illustrates testing for measurements made on a patient's handfor maximum key pinch force (MKF).

FIG. 18 is a graph comparing mean intracarpal tunnel pressures measuredat the five standardized proximal-to-distal locations 150 for handrelaxed and pinch activities.

FIG. 19 is a graph comparing mean intracarpal tunnel pressures duringhand relaxed, fingers flexed, and grip activities at the fivestandardized proximal-to-distal locations.

FIG. 20 is a graph comparing mean intracarpal tunnel pressures adjacentHH before and after release of the transverse carpal ligament

DETAILED DESCRIPTION OF INVENTION

Referring more specifically to the drawings, for illustrative purposesthe present invention is embodied in the apparatus generally shown inFIG. 1 through FIG. 20. It will be appreciated that the apparatus mayvary as to configuration and as to details of the parts, and that themethod may vary as to the specific steps and sequence, without departingfrom the basic concepts as disclosed herein.

FIGS. 1-20 detail methods and apparatus for injecting an agent or druginto at least a part of the flexor retinaculum, or tissue adjacentthereto, to treat and relieve the symptoms of CTS. One aspect isinjection of a drug in a dose that can sufficiently weaken thestructural integrity of the collagen fibers that form the flexorretinaculum. The second aspect is to induce sufficient tensile stress inthe weakened collagen fibers so that they either rupture or their lengthincreases as a result of fiber growth over time.

In a preferred embodiment, an agent containing collagenase is used forweakening the structural integrity of collagen fibers. Collagenase isproduced naturally by the body and is essential for the normalremodeling of tissues composed of collagen. In particular, an injectableform of collagenase, clostridium histolyticum (Xiaflex), is injected inor near the flexor retinaculum.

The dosage amount and concentration of collagenase used for treatment ofCTS may comprise a single injection of up to 0.9 mg of collagenase,wherein the total volume of the concentration injected is less than 0.5ml. If a single injection does not weaken the collagen adequately toenable failure of the fibrous cords, up to four additional injections ofup to 0.9 mg may be performed.

Alternatively, corticosteroids or any other drug that weakens thestructural integrity of collagen may be used. While injections ofcorticosteroids provide temporary relief of the symptoms in patientswith CTS, the drug is typically injected into the synovium thatsurrounds the contents of the carpal tunnel, not into or directlyadjacent the flexor retinaculum as provided in the system of the presentinvention.

In other areas of the body where corticosteroids are used for thetreatment of painful soft tissue injuries (tennis elbow, medialepicondylitis, achilles tendonitis and plantar fasciitis), thecorticosteroid frequently weakens the collagen fibers of the tendon orligament after multiple injections. This results in a sudden rupture ofthe tendon, either along its length or at its origin or insertion intobone, when tensile load from active muscle use is applied to theweakened collagen fibers. The various corticosteroids, their dosageamounts and concentrations typically used for the treatment of thesepainful soft tissue injuries would be effective for injecting eitherinto any part of or adjacent to the flexor retinaculum, particularlyadjacent to the palmar side, to weaken the structural integrity of itscollagen fibers

In one embodiment, an agent comprising a combination of collagenase andcorticosteroids is injected at or near the flexor retinaculum for thetreatment of patients with CTS. Because of the anti-inflammatory effectof corticosteroids, a combination of corticosteroid with collagenase mayprovide improved relief of symptoms. One of the known adverse reactionsfrom a collagenase injection is inflammation. A corticosteroid may beeither mixed together with the collagenase in the same dose that isinjected into the flexor retinaculum or injected separately from thecollagenase injection. If the corticosteroid is injected separately, itmay be injected either prior to, at the same time as, or subsequent tothe collagenase injection. A corticosteroid injected separately may beadministered either into the carpal tunnel synovium, into any part ofthe flexor retinaculum or adjacent the flexor retinaculum.

In another embodiment, the injection of a corticosteroid, collagenase orother agent may be deposited into the synovium that surrounds thecontents of the carpal tunnel. In this case, the intent is not to weakenthe structural integrity of the flexor retinaculum, but is to relievethe symptoms of carpal tunnel syndrome; similar to what a standardsteroid injection does now.

The present invention details an injection/agent delivery device to aidwith safely and accurately injecting an agent as described above atdesired locations either into or directly adjacent the flexorretinaculum. FIG. 1 shows one embodiment of an injection device 10according to the invention for both identifying the flexor retinaculumof the carpal tunnel using ultrasound imaging and injecting a drug intoany part of or adjacent to the flexor retinaculum. In the embodimentshown, injection device 10 comprises an imaging detector 12 held in aclamp 14, a needle guide 16, and an injection needle 18 with itsattached syringe 20 containing the drug 34.

The imaging means 12 can be any standard noninvasive imaging detectortypically used for guiding injection needles. In the preferredembodiment, the imaging detector 12 is a standard commercially availableultrasound transducer connected via cable 37 to an ultrasound imagingmonitor 39 having both hardware and software capable of producing highquality images of the flexor retinaculum 22 and other associated anatomyof the wrist and hand. In a standard ultrasound system, the imagemonitor 39 is remote from the imaging detector 12. To facilitate theprocedure of injecting while imaging, it may be advantageous to locatethe image monitor 39 adjacent the hand that is being imaged.

While holding the imaging detector 12 against the palmar skin 24 andadjusting its position, the physician can observe on a display monitoracceptable images of both the flexor retinaculum 22 and vital anatomicfeatures that require avoidance during injection, including the mediannerve, ulnar nerve, ulnar artery, and flexor tendons to the fingers. Inaddition, ultrasound can be used to identify the hook of the hamate 32,which is the anatomic attachment of the stiffest portion of the flexorretinaculum. It is at this location where the median nerve is the mostcompressed in the carpal tunnel. From the images, the flexor retinaculum22 can be both visually identified and its palmar-to-dorsal depthcomputed relative to a fixed reference position. In addition, havingreal-time images of the injection needle with respect to the anatomy ofthe carpal tunnel enables more accurate and repeatable injections of adrug at specific locations.

Other standard commercially available imaging devices such as MRI,X-ray, or the like, may be used for imaging the hand during theprocedure to facilitate guidance of the injection needle 18. However,ultrasound imaging offers certain advantages, including real-time imagesof the flexor retinaculum 22 as the injection needle 18 and drug 34 aredeployed into it and no radiation exposure to the patient. It is alsoappreciated that the needle guide 16 may be made integral with thehousing of the imaging detector 12.

With the injection device 10 held by the physician, the imaging surface38 of the imaging detector 12 can be positioned on the palm of thepatient's hand 24 either longitudinally, as shown in FIG. 1, or rotated90 degrees about the longitudinal axis of the imaging detector Z_(D) toa transverse position, as shown in FIG. 2.

Alternatively, two imaging detectors (not shown) may be either containedin a single clamp 14, or held separately, one oriented to provide alongitudinal image and the other oriented to provide a transverse imageof the patient's carpal tunnel anatomy. The two imaging detectors couldbe either identical, or have differing physical dimensions and/orperformance capabilities. Using this arrangement, two images of thecarpal tunnel anatomy may be displayed simultaneously on the imagemonitor.

In an alternative embodiment, a single imaging detector 12 can be usedwith software (not shown) in the image monitor 39 that has thecapability of providing three-dimensional images using either mechanicalor electronic switching that scans using both longitudinal andtransverse imaging.

To both enhance the acoustic quality of the ultrasound signals andenable ease of positioning the imaging detector 12, a standardcommercially available aqueous ultrasound gel, or other suitablematerial for conducting sound, is applied to the palm of the patient'shand 24 prior to imaging. When the desired image of the flexorretinaculum 22 is obtained, the needle guide 16 is adjusted in apalmar-dorsal direction Y_(P-D), along the axis of adjustment of theneedle guide A_(N-G), to align the injection needle 18 with the desiredlocation for injection. The axis along which the needle guide isadjusted A_(N-G) is parallel to the longitudinal axis of the imagingdetector Z_(D).

Needle guide 16 is slideably coupled to clamp 14 via a dovetail joint 35(see FIG. 5) that allows controlled translation of the needle guide 16with respect to the clamp 14 in only the Y_(P-D) direction. Ultrasounddepth information displayed on the image monitor is used to compute thepalmar-dorsal depth from the palm of the hand 24 to the flexorretinaculum 22. The desired depth is set using the indicator marks 28(comprising increments in either mm or inches), which reference thepalmar-dorsal position of the needle guide 16 to the clamp 14.

It is appreciated that surface 38 may comprise a surface of the detector12, or the clamp 14 housing the detector 12. In one embodiment, thedevice 10 may not have a detector 12. In this mode, the clamp 14 merelyacts as a housing or base that provides a reference surface 38 to restthe device 10 on the palm 24 of the hand. Anatomical measurements and orimaging of the patient may previously be conducted (e.g. via a pre-opdiagnostic or the like procedure), such that the physician sets thedesired depth in the palmar-dorsal direction Y_(P-D) and advances theneedle 18 to the desired treatment location.

Having the patient flex and extend their fingers during imaging may beused to highlight the contrast between the mobile flexor tendons and thestatic flexor retinaculum, enabling better identification of the dorsalmargin of the flexor retinaculum.

With the needle guide 16 set to the desired position, and the patient'swrist held in some appropriate degree of extension, the physicianadvances the injection needle 18 along a proximal-to-distal directionX_(P-D) through the guide aperture 36. The long axis N_(F-R) of hole 36is preferably parallel with the imaging surface 38 of the imagingdetector 12, so that the needle 18 enters the patient's skin proximal tothe distal wrist crease and is advanced until the needle's tip reachesthe desired treatment location. Advancement of the needle's shaft 18 isdisplayed on the imaging monitor 39 via detector 12. Under imageguidance, the injection needle 18 enters the flexor retinaculum 22 alongits longitudinal axis A_(FR).

The longitudinal axis A_(F-R) of the flexor retinaculum 22 is defined asan axis that extends from proximal to distal, intersecting generallyperpendicular to the distal edge of the flexor retinaculum 22. Toprevent soft tissue from entering the bore of the injection needle 18during insertion and causing blockage of the injection needle 18, astandard commercially available removable stylet that fits within thebore can be used and then removed prior to dispensing the drug 34.

As shown in FIG. 1, the imaging surface 38 of the imaging detector 12(and needle aperture axis N_(F-R)) is positioned by the physician to beparallel with the longitudinal axis of the flexor retinaculum A_(F-R).This is preferably indicated on the imaging monitor 39 as being parallelwith either the upper or lower edge of the monitor screen (not shown).In this position, the long axis N_(F-R) of the injection needle 18 iscoincident with the longitudinal axis A_(FR) of the flexor retinaculum22, entering it at its proximal extent, and is advanced distally withthe drug 34 deposited at either a single or multiple locations.

Flow of the drug 34 from the syringe 20 into the flexor retinaculum 22may be readily observed visually on the imaging monitor 39. Ifadditional enhancement of the flow dynamics of the drug 34 is desired,commercially available microspheres or any other commercially availableimage-enhancement particles may be added to the drug 34 prior toinjection.

A number of target locations for injection may be advantageous. Oneinjection location is where the flexor retinaculum 22 is stiffest andtherefore, its structural integrity requires more substantial weakeningof its tensile strength. The transverse stiffness of the flexorretinaculum 22 varies from the proximal to distal borders of the carpaltunnel. The stiffness of the ligament is generally the stiffest at alocation within the central portion of the flexor retinaculum 22, calledthe transverse carpal ligament 30. This location, where the ligamentalso is the thickest, coincides with the transverse carpal ligament'sattachment between the hook of the hamate bone 32 and the ridge of thetrapezium bone. In addition, it is at this location within the carpaltunnel where the pressures on the median nerve are the greatest. Imagingcan be used to both identify the transverse carpal ligament 30 andprecisely guide the injection needle 18 into it. Another locationrequiring precise image-guided injection is where the transverse carpalligament 30 attaches to the bones of either the hook of the hamate bone32 or the trapezium bone (not shown). At this location, the collagenfibers blend into bone, making the ligament stiffer.

Another location for injection requiring precise image guidance includesinto the flexor retinaculum directly palmar to the median nerve.

If a sufficient amount of drug 34 cannot be injected into the flexorretinaculum 22, the drug 34 may be injected directly adjacent the flexorretinaculum 22. Using the depth information from the ultrasound, theneedle guide 16 is preferably positioned in the palmar-dorsal directionY_(P-D), along the axis of adjustment of the needle guide A_(N-G), priorto insertion of the injection needle 18 so that the injection needle 18is either more palmar or dorsal to the flexor retinaculum 22. Underimage guidance, the injection needle 18 may be inserted and preciselyplaced adjacent the ligament, either palmar or dorsal, and the drug 34deposited. Locations that may be advantageous for deposition of the druginclude adjacent to the flexor retinaculum directly palmar to the mediannerve, adjacent to the flexor retinaculum within the carpal tunnel,adjacent to the flexor retinaculum within the carpal tunnel adjacent themedian nerve, and adjacent to the flexor retinaculum within the carpaltunnel ulnar to the median nerve. Diffusion of the drug 34 into theflexor retinaculum 22 is sufficient to cause weakening of the collagenfibers.

In the embodiment of the invention shown in FIG. 1, the longitudinalaxis N_(F-R) of the guide hole 36 is perpendicular to the axis ofadjustment A_(N-G) of the needle guide 16. Alternatively, the guide hole36 can traverse the needle guide 16 at an angle so that when theinjection needle 18 is inserted through the guide hole 36, it intersectsthe flexor retinaculum 22 at an acute angle. FIG. 1 shows two examplesof alternative guide hole 36 locations that enable insertion of theinjection needle 18 along axes B_(F-R) & C_(F-R) that aim toward theflexor retinaculum 22, but are not in the proximal-to-distal directionX_(P-D). With these alternative guide hole 36 locations, the injectionneedle 18 may enter the patient's skin distal to the distal wristcrease. Additional locations of the guide hole 36 in the needle guide 16also are possible.

By using one of these alternative placements of the guide hole 36 in theneedle guide 16, various additional attachment positions of the needleguide 16 to the clamp 14 may be used. In FIG. 1 the needle guide 16 isattached to the clamp 14 on its proximal end. Alternatively, the needleguide 16 could be attached on the radial, ulnar, or distal sides of theclamp 14. By using these alternative positions, the injection needle 18can be inserted either into any part of or adjacent to the flexorretinaculum 22 using image guidance as the injection needle 18 entersthe field of view.

FIG. 3 shows an injection device 49 with a guide tube 40 inserted intothe carpal tunnel dorsal to the flexor retinaculum 22. Using the samemethod described for insertion of an injection needle, the needleguide/adjuster 16 is positioned in a palmar-dorsal direction Y_(P-D) toobtain the desired entry location of the guide tube 40. Needle guide hasan expanded bore 36 for accommodating the guide tube 40. The guide tube40 is inserted as a conduit for alternative measurement and treatmenttechniques that are used either in combination with an injection of theflexor retinaculum 22 or as separate procedures. One alternative is adiagnostic measurement of the carpal tunnel pressure using a standardcommercially available pressure sensor 42. Either prior to or followingtreatment to the flexor retinaculum 22 with a drug, the pressure sensor42 is inserted through the guide tube 40 into the carpal tunnel wherethe pressure is measured. Because the greatest pressure has been shownto occur both adjacent the dorsal surface of the flexor retinaculum 22and adjacent the hook of the hamate 32, it is desirable to measure thepressure in this location. The use of the imaging detector 12 can bothaid and confirm placement of the pressure sensor 42 at this location.

In another embodiment, the guide tube 40 is configured to directpositioning of a cutting probe 44 to the treatment location. Cuttingprobe 44 may comprise a cutting blade 45, or may comprise a standardhypodermic needle with the bevel on the needle acting as a cuttingblade. Cutting may be used to either create a space adjacent to theflexor retinaculum or create a separation in the fibers of the flexorretinaculum to enhance the ability of the flexor retinaculum to absorbthe delivered drug or agent. Guide tube 40 may be used to positionneedle 18 in a similar manner for drug delivery to the desired treatmentsite. In addition, cutting of the fibers of the flexor retinaculum willweaken the segment of the ligament receiving the injection. The cuttingprobe 44 may also be used to perform division of the flexor retinaculum22.

FIG. 4 shows another embodiment of an injection device 50 according tothe invention for both identifying the flexor retinaculum of the carpaltunnel and injecting a drug into any part of the flexor retinaculum oradjacent tissue region. The injection device 50 shown in FIG. 4 issimilar to that shown in FIG. 1, but utilizes an additional attachmentmeans for both aligning and supporting the imaging detector 12 andneedle guide 16 on the patient's hand.

Both rotational and translational alignment of the imaging detector 12shown in FIG. 1 are performed manually by the physician as he/she holdsthe imaging detector 12 and positions it to obtain optimal images of thedesired anatomy. This requires the physician to hold the imagingdetector 12 while trying to keep both the desired image and correctorientation of the needle guide 16. The injection device 50 shown inFIG. 4 provides the same rotational and translational alignments of theimage detector 12 and needle guide 16, but maintains both support andalignment of the imaging detector 12 when the physician releases theirhold of the image detector 12.

Clamp 14 secures the imaging detector 12, and is attached to a clevis 52having opening 68 via a pin 54. Attachment is facilitated using a pin 54to enable rotation of the clamp 14 in a palmar-dorsal direction R_(P-D)about the longitudinal axis A_(PD) of the pin 54 as shown in FIG. 5. Onthe opposite end of the clevis 52 is a link 56 that slides into both theclevis 52 and a pivot joint housing 58. Link 56 permits both translationbetween the clevis 52 and pivot joint housing 58 in a proximal-to-distaldirection T_(P-D) and rotation in an internal-external direction R_(I-E)about the longitudinal axis A_(IE) of the link 56 as shown in FIG. 5. Ahole in the distal end of the pivot joint housing 58 slides onto a pivotpin 60. Pivot pin 60 provides rotation of the injection device 50 in theradial-ulnar direction R_(R-U) about the longitudinal axis A_(RU) of thepivot pin 60 as shown in FIG. 5. By having this rotationaladjustability, the imaging detector can be positioned to both view thecritical anatomy that is of interest from radial to ulnar, including thehook of the hamate, ulnar artery, and ulnar nerve, and identify a safepath for the injection needle.

The opposite end of the pivot pin 60 inserts into a rod 62 that isconfigured to be placed in the palm of the patient's hand 24 adjacentthe metacarpophalangeal joints of the fingers. To secure the rod 62 tothe patient's hand, an elastic band 64 is wrapped around each end of therod 62 and then around both the dorsal sides of the fingers and hand asshown in FIG. 4 and FIG. 5. In addition to holding the rod 62 stable inthe patients hand, the elastic band 64 holds the metacarpophalangealjoints of the fingers in flexion. Once the desired image of the flexorretinaculum or surrounding anatomy is obtained, each adjustment can belocked to prevent additional motion in any of the adjustable directions;R_(P-D), T_(P-D), R_(R-U), R_(I-E), and Y_(P-D). For example, it may bedesirable to have the positioning of the imaging surface 38 of theimaging detector 12 locked in a parallel orientation with respect to thelongitudinal axis A_(FR) of the flexor retinaculum 22.

FIG. 6 shows an alternative injection device 55 comprising a guide tube70 for insertion into the carpal tunnel dorsal to the flexor retinaculum22 (or adjacent tissue region). Similar to FIG. 3, the guide tube 70 isinserted as a conduit for alternative measurement and treatmenttechniques that are used either in combination with an injection of theflexor retinaculum 22 or as separate treatments. For example, diagnosticmeasurement of the carpal tunnel pressure may be performed using apressure sensor 72. Either prior to or following treatment to the flexorretinaculum 22, the pressure sensor 72 is inserted through the guidetube 70 into the carpal tunnel where the pressure is measured.

Cutting probe 74 may also be delivered to the treatment site to eithercreate a space adjacent to the flexor retinaculum or create a separationin the fibers of the flexor retinaculum for deposition of the drug.Cutting probe 74 may comprise a cutting blade, or may comprise astandard hypodermic needle with the bevel on the needle acting as acutting blade. Either of these will enhance the ability of the flexorretinaculum to absorb the drug. In addition, cutting of the fibers ofthe flexor retinaculum will weaken the segment of the ligament receivingthe injection. Furthermore, the cutting probe 74 may be used to performdivision of the flexor retinaculum 22.

With both the attachment to the patient's hand and the adjustabilityprovided by the apparatus shown in FIG. 6, the adjuster 76 can be usedto move the guide tube 70 palmar along the palmar-dorsal directionY_(P-D) until its palmar surface contacts the dorsal surface of theflexor retinaculum 22. By squeezing the tissues between the palmarsurface of the imaging detector 12 on the palm of the patient's hand 24and the palmar surface of the guide tube 70, the guide tube 70 becomesstabilized against the deep surface of the flexor retinaculum 22.

FIG. 7 shows an alternative method of insertion of the guide tube 70palmar to the surface of the flexor retinaculum 22 by moving theadjuster 76 along the palmar-dorsal direction Y_(P-D) prior to insertionof the guide tube 70 into the patient's hand. A similar insertion methodmay be used with the injection device 149 shown in FIG. 3 using theadjuster or needle guide 16. An insertion position of the guide tube 40or 70 palmar to the surface of the flexor retinaculum 22 could be usedfor insertion and treatment using the cutting probe 44 or 74 asdescribed previously in this application.

It may be desirable for the physician to view both transverse andlongitudinal images of the carpal tunnel while performing injection ofthe flexor retinaculum. FIG. 8 shows another embodiment of the injectiondevice shown in FIG. 4, but with the imaging detector 12 held by acircular clamp 82. The circular clamp 82 enables rotation of the imagingdetector 12 within circular opening 84 in a longitudinal-transversedirection R_(L-T) about the longitudinal axis of the imaging detectorZ_(D), as shown in FIG. 2, so that images can be obtained easily ineither position.

To provide stable images, the imaging detector 12 can be secured ineither the longitudinal or transverse position. Alternatively, twoimaging detectors either contained in a single clamp or held separately,one oriented to provide a longitudinal image and the other oriented toprovide a transverse image of the patient's carpal tunnel anatomy. Usingthis arrangement, two images of the carpal tunnel anatomy could bedisplayed simultaneously on the image monitor. Another alternativeembodiment is a single imaging detector with software that has thecapability of providing three-dimensional images using either mechanicalor electronic switching that scans using both longitudinal andtransverse imaging.

FIGS. 9 and 10 show another embodiment of an injection device 100according to the invention for both identifying the flexor retinaculumof the carpal tunnel and injecting a drug into any part of or adjacentto the flexor retinaculum. The injection device 100 shown in FIGS. 9 and10 is similar to that shown in FIG. 4, but instead of the alignmentfixture attaching to the patient's hand, it utilizes a fixed base 130that is used to support and hold both the patient's hand and thealignment fixture. The injection device 100 shown in FIGS. 9 and 10 alsoprovides the same rotational and translational adjustments for alignmentof the imaging detector 12 and needle guide 16 as those provided by theinjection device 50 shown in FIG. 4; thereby maintaining both supportand alignment of the imaging detector 12 and needle guide 16 when thephysician releases their hold of the imaging detector 12.

The top surface of the base 130, where the patient's forearm and handare supported, consists of a flat surface 112 where the patient'sforearm rests and an angled surface 132 that supports the patient'shand. Positioning the back or dorsal surface 25 (see FIG. 4) of thepatient's hand (which has less soft tissue than the palmar surface 24)on the angled surface 132, the hand may be reliably positioned on thesecond surface in a stable manner that allows little, if any motion ofthe hand with respect to the second surface. The angle between the twosurfaces is aligned with the patient's wrist to position the wrist in anappropriate degree of extension to accommodate entry of the injectionneedle 18. With the patient's hand resting on the angled surface 132,both their index and little fingers may be constrained by straps 114that prevent these two fingers from flexing while allowing the other twofingers and thumb free to flex. The clamp 14 that secures to the imagingdetector 12 is attached to an arm 144 that has a hole 116 in its distalend. A rotational adjustment screw 118 is used to secure the arm 144 toa positioning rod 138 that inserts through the hole 116. Loosening ofthe rotational adjust screw 118 enables rotation of the arm 144 aboutthe longitudinal axis A_(PR) of the positioning rod 138 to providetilting of both the imaging detector 12 and needle guide 16 in aninternal-external direction R_(I-E).

Loosening of the translational adjustment screw 140 on the slide block120 permits translation of the arm 144 along a slot 136 in thepositioning rod 138, allowing translation in a proximal-distal directionT_(p-D). The proximal end of the positioning rod 138 inserts into apivot block 122 that attaches to a clevis clamp 134 using a tiltadjustment screw 124. Loosening of the tilt adjustment screw 124 allowsrotation of the pivot block 122 about the longitudinal axis of the tiltadjustment screw A_(AS), permitting the arm 144, imaging detector 12,and needle guide 16 to rotate in a palmar-dorsal direction R_(P-D).

Loosening of the clevis clamp screw 146 allows rotation of the clevisclamp 134 about the longitudinal axis A_(P) of the post 126, permittingthe arm 144, imaging detector 12, and needle guide 16 to rotate in aradial-ulnar direction R_(R-U). The longitudinal axis A_(P) of the post126 is both perpendicular to and intersects with a longitudinal axisA_(RL) that forms the contact line between the patients ring and longfingers. An adjustment knob 142 is used to translate the post 126 in apalmar-dorsal direction Y_(P-D), providing translation of both theimaging detector 12 and needle guide 16 along the same directionY_(P-D).

In the embodiments shown in above, the drug 34 is contained in a syringe20 or the like. In an alternative embodiment, the drug 34 can becontained in a pre-packaged cartridge (not shown) that is pre-filledwith the appropriate dosage of drug 34. This pre-filled cartridge canthen be inserted into any suitable standard manual drug delivery devicewith a needle. A pre-packaged dosage of the drug 34 may also includeparticles to enhance the image of the drug 34. Other alternativeembodiments include any suitable drug delivery device that uses apressure mechanism to dispense the drug.

Prior to insertion of any of the previously described injection needles,pressure sensors, guide tubes, or cutting probes, local anesthesia maybe administered by injecting it into the patient's wrist or hand.Injection of local anesthesia may be performed using either theinjection needles described or a separate standard injection needle.Local anesthesia may be injected either alone separately or combinedwith the drug 34.

The flexor retinaculum inherently has a physiologic tension that existsprimarily in a radial-to-ulnar direction as a result of its anatomy. Theexact mechanics related to this tensile stress aren't completelyunderstood. However, attachments of the thenar and hypothenar muscles tothe collagen fibers of the flexor retinaculum contribute to this tensilestress. This tensile stress, which determines the strength of the flexorretinaculum, exists in order to maintain the structural integrity of thecarpal tunnel during both static and dynamic hand activities. Whetherthe hand is at rest or active, the tension in the flexor retinaculum issufficient to balance the forces acting on it; one of which is thevariable pressure that exists within the carpal tunnel. It is thispressure that exists within the carpal tunnel that can be used toincrease the stress in the collagen fibers of the flexor retinaculumonce they have been weakened by injection of a drug.

With the hand at rest, a pressure exists within the carpal tunnel, andthat pressure is greater in subjects with CTS than those without. Duringboth forceful grip and pinch, pressure within the carpal tunnelincreases substantially, thereby causing an increase in tensile stressin the flexor retinaculum.

In twenty patients with CTS, pressure was measured within the carpaltunnel, adjacent the flexor retinaculum, as patients actively used theirhands. As patients gripped a grip dynamometer using 25% maximum grip,50% maximum grip, and maximum grip, the pressures adjacent the flexorretinaculum increased significantly. The mean peak pressure duringmaximum grip was 1151 mm Hg, with pressures as great as 2500 mm Hgrecorded. As patients pinched a pinch dynamometer using maximum pinch,the pressures adjacent the flexor retinaculum reached a mean peak of 621mm Hg, with pressures as great as 1133 mm Hg recorded. Test resultsshowed that pressures in the carpal tunnel were up to eight timesgreater than those previously recorded.

To produce the required tensile stress in the weakened collagen fibersof the flexor retinaculum, the physician can prescribe an active handuse protocol for the patient.

During a period of time after injection of the drug, while the drugremains effective, the inherent stress in the flexor retinaculum may besufficient, with the weakened collagen fibers, to cause either ruptureof the collagen fibers or an increase in their length resulting fromtheir growth over time. However, if the inherent stress in the flexorretinaculum is insufficient to obtain the desired improvement in patientsymptoms, the physician should prescribe for the patient to performforceful and repetitive gripping or pinching exercises. These exercisesmay be performed either with or without the aid of either a grip devicethat fits in the palm of the patient's hand or a pinch device that fitsbetween the thumb and one or more fingers. Grip or pinch exercises thatachieve pressures comparable to those recorded during the study wouldprovide the increase in tensile stress necessary to cause the collagenfibers composing the flexor retinaculum to either abruptly fail and/orincrease in anatomic length. To ensure that the patient performs theprescribed grip or pinch exercises, any standard commercially availablegrip or pinch dynamometers can be used that have the capability toprovide either visual or auditory feedback to the patient of both themagnitude of grip or pinch force and the number of grips or pinches thathave been performed. Grip or pinch exercises are continued daily untilthe drug is no longer effective at weakening the structural integrity ofthe collagen. Even after the drug affect has expired, hand exercisesshould be continued to maintain the increased length and decreasedstrength of the flexor retinaculum.

FIG. 11 illustrates system 200 comprising a standard grip dynamometer202. FIG. 12 shows system 210 having pinch dynamometer 208. Standardcommercially available dynamometers are manufactured by both JAMARTechnologies, JTECH Medical, and others. Each dynamometer can beattached through cabling 204 to a data acquisition and display module206. Display module 206 aids the patient by displaying their forcemagnitude and number of grip or pinch cycles while performing theprescribed grip or pinch exercises. In addition, the patient's forcedata is stored in the data acquisition and display module 206 andprovides the physician with a record of the force magnitudes achieved,the amount of time the patient spent at each force level, and number ofcycles of each.

Alternatively, an exercise device may apply force to the palm of thepatient's hand that increases the pressure within the carpal tunnel.However, using this method, the stress produced in the flexorretinaculum may be less than that produced by a patient initiated force.In the experiments of the present invention, the pressure produced inthe carpal tunnel, adjacent the flexor retinaculum, when an externalgrip dynamometer was used to apply the same force to the palm of thepatient's hand, was one-half of what the pressure was when the patientgenerated the force themselves using the same grip dynamometer. It isduring active grip activities with advanced degrees of finger flexionthat the lumbrical muscles of the hand migrate proximally into thecarpal tunnel, providing the dilating force necessary to cause themaximum increase in tensile stress in the flexor retinaculum.

If complete relief of the symptoms of CTS is not achieved with either asingle dose injection or multiple doses during a single day, additionalinjections using the methods described previously in this applicationcan be performed over time, followed by a prescribed hand exerciseroutine. Subsequent injections may be based on either the patient'ssymptoms or the active life of the drug.

Alternatively, additional injections may be facilitated by inserting astandard commercially available catheter (not shown), with or withoutmultiple perforations, via the guide tube 40 shown in FIG. 3 or guidetube 70 shown in FIG. 7. The gauge of guide tube 70 may be modifiedaccordingly. After insertion, the catheter may be left in place toprovide intermittent injections of a drug either into or adjacent theflexor retinaculum.

The methods and apparatus described in FIGS. 1-12 above for thetreatment of carpal tunnel syndrome may also be used for the treatmentof other diseases involving a ligament that constrains either a tendonor nerve, including, but not limited to, tarsal tunnel syndrome of thefoot, trigger finger, trigger thumb, tendonitis of the long head of thebiceps tendon in its groove in the proximal humerus at the shoulderjoint, cubital tunnel syndrome, and DeQuervains tendonitis at the wrist.Injection of a drug either into or adjacent the ligaments that form thepulleys for these anatomical locations would prove effective fortreating these diseases.

As the mechanical properties of the flexor retinaculum change over timefollowing the injection, relief of the patient's symptoms may be used tomonitor the effectiveness of the injection. Other alternative methodsmay be used to monitor the effectiveness of the injection includingnerve conduction tests and pressure measurements within the carpaltunnel. Another alternative method is to monitor the physical behaviorof the flexor retinaculum using ultrasound imaging. A series ofultrasound images following treatment of the flexor retinaculum can beused to monitor the response of the flexor retinaculum to the drug andexercise program. Another alternative to monitor the effectiveness ofthe injection includes blood and/or urine samples to assay for thebreakdown products of collagen in general and collagen that makes up theflexor retinaculum in particular.

The methods and apparatus of the present invention provide for injectionof a drug either into any part of or adjacent to the flexor retinaculumfollowed by increasing the tensile force to the weakened collagen fibersof the flexor retinaculum to relieve the symptoms of CTS. This providesseveral advantages over prior techniques for the treatment of CTS,including (a) prevention of excessive palmar displacement of the digitalflexor tendons and/or median nerve created by the traditional divisionof the flexor retinaculum; (b) avoiding entrapment of the median nerveand/or flexor tendons in a more nearly subcutaneous palmar position inwhich these structures are relatively or absolutely entrapped in scartissue that occurs as a result of the healing process for the surgicallydivided flexor retinaculum; (c) maintenance of relative stability of theentire flexor retinaculum as a unit, e.g., the cut edges of thecompletely divided flexor retinaculum can evert (turn outward orsubcutaneously) as a result of the spread of the carpal tunnel, as wellas the pull of the thenar and hypothenar muscle groups, particularly thethenar muscles on the radial side of the divided flexor retinaculum; (d)preservation of a gliding synovial surface on the deep side of theflexor retinaculum for the digital flexor tendons and median nerve; (e)potential decreased morbidity from greater stability of the origin ofthe muscles that arise from the flexor retinaculum, particularly thethenar muscles responsible for thumb opposition, pinch and grasp; (f)decrease in the amount of time necessary to return to activities ofdaily living and work as a result of less trauma caused to the flexorretinaculum; (g) reduced costs of treating CTS, including performing theligament injection as an office procedure rather than an operating roomprocedure; (h) the inherent safety of an injection needle that is guidedusing ultrasound imaging compared with a cutting blade used for open orendoscopic carpal tunnel release; (i) avoiding shear stress on themedian nerve where the ligament/fascia division abruptly stops,typically at the proximal end of the incised ligament/fascia; and (j)the decreased potential for a hematoma in the carpal tunnel that may, asthe hematoma evolves, entrap the median nerve in scar tissue.

Example

Tests were performed to better understand the dynamics of intracarpaltunnel pressure from proximal-to-distal in patients with CTS duringquantified active use of the hand both before and after division of thetransverse carpal ligament.

The test included 20 patients (21 hands: 10 left, 11 right), 11 femaleand 9 male (mean age: 55 years; range: 33-81 years), diagnosed withidiopathic CTS. In each patient, the diagnosis of idiopathic CTS wasbased on clinical signs and symptoms and confirmed by preoperativeelectrophysiological studies. The mean time from diagnosis to surgerywas 2 years and 11 months (range: 2.5 months-15 yr. 3 months.). Inaddition, at least one steroid injection was administered to twenty ofthe affected hands and was used to confirm the diagnosis based on reliefof symptoms. Patients were excluded from the study if there was anyhistory of peripheral neuropathy, diabetes, thyroid disease, anatomicabnormalities of the wrist or hand, inflammatory joint disease, previoustraumatic nerve injury, previous wrist surgery, vasospastic disorders orsympathetic dystrophies, psychiatric disorders, chronic renal disease,or previous carpal tunnel release. The hospital institutional reviewboard approved the study protocol and both informed consent and HIPAAauthorization were obtained from each patient.

Referring to FIG. 13, prior to surgery for CTS, an anterior-posteriorradiographic view was obtained on each patient to identify theproximal-to-distal distance between the distal wrist crease (DWC) 152and the center of the Hook of the Hamate (HH) 32. This dimension, DWC-HH(mean: 2.0 cm; range: 1.6-2.5 cm), was used for two purposes. The firstpurpose was to establish a visual landmark on the skin, at the time ofsurgery, identifying HH relative to the easily identifiable DWC. Thesecond purpose was to standardize the proximal-to-distal locations wherepressure measurements were recorded based on the individual anatomy ofeach patient.

As shown in FIG. 13, five measurement locations 150 were chosen andstandardized based on the DWC-HH measurement.

Also prior to surgery, maximum grip and pinch forces were determined foreach patient. Maximum grip force was measured using a handheld gripdynamometer 202 (see FIG. 15) (Griptrack; Jtech Medical, Salt Lake City,Utah) calibrated for 0 to 456 N. Patients performed three maximum griptrials with the grip spacing set to the smallest. With this gripspacing, the mean distance between the tip of the ring finger and thepalm of the hand was 30 mm (range: 22-48 mm). From the grip trials, amean maximum grip force was computed for each patient and 75% of thatvalue was used as the patient's maximum grip force (MGF). Maximum pinchforce was measured using a pinch dynamometer 204 (see FIG. 16)(Pinchtrack; Jtech Medical, Salt Lake City, Utah) calibrated for 0 to222N. Patients performed three maximum pinch trials each using both pulpand key pinches. Mean maximum pinch forces were computed for both pulpand key pinches on each patient and 75% of these values were used as thepatient's maximum pulp pinch force (MPF) and maximum key pinch force(MKF). During both grip and pinch force measurements, patient's wristswere maintained in a neutral position. 75% of the patient's maximum gripand pinch forces were chosen as MGF, MPF, and MKF to ensure that eachpatient could achieve these forces during surgery. Once MGF, MPF, andMKF were determined, each patient practiced both achieving and holdingthe target grip and pinch force levels that they would perform duringtheir surgery, using visual feedback of the force levels.

On the day of surgery, each patient was prepared for an endoscopiccarpal tunnel release. Using the DWC-HH landmark obtained from thepreoperative radiographic view, each patient's hand was marked with thelocation of HH 32. Next, a brachial tourniquet was applied and, underlocal anesthesia, an entry wound through the fascia was createdapproximately 1 cm proximal to DWC between the flexor carpi radialis andflexor carpi ulnaris tendons. This wound at the wrist provided accessdeep to the fascia for insertion of a pressure transducer PT (see FIG.14). Two types of entry wounds were used, either an incision or apercutaneous. The incision entry, used on 13 hands, was the endoscopicportal used with the MicroAire Carpal Tunnel Release System (MicroAire,Charlottesville, Va.) that was described previously. The percutaneousentry, used on 8 hands, was created using a 13-gauge hypodermic needle(BD Medical Systems, Franklin Lakes, N.J.) with a custom-made obturator.In both entry methods, once access deep to the fascia was established, a2.5 mm probe was used to create a path from proximal to distal down thepalmar-ulnar aspect of the carpal tunnel for insertion of the pressuretransducer.

Intracarpal tunnel pressures were measured using a MIKRO-TIP pressuretransducer PT (SPC-350S; Millar Instruments, Houston, Tex.) containing aminiature semi-conductor gauge pressure sensor in a 5F catheter(cross-sectional area=2.2 mm²) calibrated for a measurement range of −50to 3000 mm Hg. The pressure transducer PT was inserted through the entrywound, along the path created down the palmar-ulnar aspect of the carpaltunnel, and aligned adjacent both HH and the dorsal surface of thetransverse carpal ligament with the sensor oriented dorsal. Thetourniquet was released (mean tourniquet time: 7 minutes; range: 4.5-11minutes) and reperfusion of the tissues was allowed (mean reperfusiontime: 8.5 minutes; range: 5-17 minutes) before pressure measurementbegan. During reperfusion, correct placement of the pressure sensor PTat HH was confirmed using fluoroscopy (see fluoroscopic image 154 inFIG. 14). In addition, a custom-made clamp 160, used to both hold andposition the pressure transducer PT, provided a visual reference of itsposition within the carpal tunnel using an external solid rod SR (FIG.14). This enabled marking the standardized pressure measurementlocations 150 on the palmar skin 24 (FIG. 15).

With the patient's upper extremity resting on an arm table, elbowextended, forearm supinated, and wrist in a neutral position, pressuremeasurements were obtained at each of the five standardized locations150 within the carpal tunnel in the following order: ¾ DWC-HH distal toHH, HH, ⅓ DWC-HH proximal to HH, ⅔ DWC-HH proximal to HH, DWC, and arepeat measurement at HH. At each location, with either minimal or nosedation, the patient performed each of the following hand activities:fingers fully extended, fingers fully flexed without grip force, 25%MGF, 50% MGF, MGF (FIG. 15), MPF (FIG. 16), MKF (FIG. 17), and fingersfully extended while an external force was applied by the physician tothe patient's hand using 25% MGF, 50% MGF, and MGF.

Intracarpal tunnel pressure was recorded simultaneously with grip force,pinch force, and external force using signal conditioning hardware(Validyne Engineering, Northridge, Calif.) with a portable dataacquisition system (Mycorder; Datastick Systems, Santa Clara, Calif.).Both grip and pinch forces were measured using the same dynamometers 202and 204 that patients used prior to surgery, but they were enclosed insterile bags. The external force was applied by the physician pressingthe same grip dynamometer 202 against the palm 24 of the patient's handin the same location where the patient held it. As the patient receivedinstructions, visual feedback of both grip and pinch force was providedto the patient, enabling each patient to both achieve and maintain thetarget force levels.

Once all pressure measurements were obtained, the pressure transducer PTwas removed, the tourniquet was reapplied, and endoscopic carpal tunnelrelease surgery was performed. After complete division of the transversecarpal ligament, the tourniquet was released, reperfusion was allowedfor five minutes, and the pressure transducer PT was reinserted into thecarpal tunnel. Pressure measurements were obtained with the transducerpositioned at a single location, HH, during the same hand activities,with the exceptions of MGF and application of an external force.

All pressure measurements were expressed as the mean±one Standard Error(SE). Using a log transformation on the data, a repeated measuresanalysis of variance was used to determine the affect of hand activity,intracarpal measurement location, and surgical division of the ligamenton intracarpal tunnel pressure. A Tukey-Kramer analysis with asignificance level of p<0.05 was used to adjust for multiplecomparisons.

Standardized pressure measurement locations resulted in mean distancesdistally from DWC of 0.7 cm (range: 0.6-1.3 cm), 1.4 cm (range: 1.1-2.0cm), 2.0 cm (range: 1.6-2.3 cm), and 3.5 cm (range: 2.9-4.1 cm) (FIG.13).

Because of variations in pressure measurement protocol, data from allpatients for each hand activity were not included. FIGS. 18-20 indicatethe number of patients included for each hand activity.

FIG. 18 compares mean intracarpal tunnel pressures measured at the fivestandardized proximal-to-distal locations 150 for hand relaxed and pinchactivities. Mean pinch forces for MKF and MPF were 49 N (range: 31-64 N)and 45 N (range: 21-78 N), respectively. Measurement location had nosignificant effect on intracarpal tunnel pressure for the relaxed hands.No significant differences existed between the pressures at any onelocation when compared with each of the other four locations (p>0.05).Measurement location did have a significant effect on intracarpal tunnelpressure during pinch activities. Pressures were significantly greaterat HH than at DWC, ⅔ DWC-HH Proximal, and ¾ DWC-HH Distal during bothMKF and MPF (p<0.05). In addition, pressures were significantly greaterat ⅓ DWC-HH Proximal than at DWC during both MKF and MPF (p<0.05).

Although there were no significant differences in pressures between MKFand MPF at any of the five locations 150 (p>0.05), pinch activities hada significant effect on intracarpal tunnel pressure, but were dependenton location. Compared to hand relaxed, pressures during both MKF and MPFwere significantly greater at both ⅓ DWC-HH Proximal and HH (p<0.05). Inaddition, pressures during MPF were significantly greater than thosewith a relaxed hand at ¾ DWC-HH Distal (p=0.007).

During the pressure measurement sequence for each hand activity, ameasurement of the pressure at HH was repeated after all other pressureswere recorded. This repeat measurement validated the repeatability ofthe pressure measurement system for each hand activity and patient. Forthe relaxed hand, MKF, and MPF, the final repeat measurement at HHconfirmed that there was no significant difference between the initialand final pressures measured at HH (p=1).

FIG. 19 compares mean intracarpal tunnel pressures during hand relaxed,fingers flexed, and grip activities at the five standardizedproximal-to-distal locations. Mean grip forces for 25% MGF, 50% MGF, andMGF were 53 N (range: 31-75 N), 98 N (range: 62-139 N), and 185 N(range: 125-281 N), respectively. Measurement location had a significanteffect on intracarpal tunnel pressure, but was dependent on handactivity. During MGF, pressures at HH were significantly greater thanthose at the four other locations (p<0.05). In addition, pressures atDWC were significantly less then those at both ⅓ DWC-HH and ¾ DWC-HHDistal (p<0.05). During both 50% MGF and fingers flexed, pressures at HHwere significantly greater then those at DWC, ⅔ DWC-HH Proximal, and ¾DWC-HH Distal (p<0.05). During 25% MGF, only the pressures at DWC weresignificantly less then those at HH (p=0.03). Also, during fingersflexed, pressures at ⅓ DWC-HH were significantly greater than those at ¾DWC-HH Distal (p=0.01).

Hand activity had a significant effect on intracarpal tunnel pressure,but was dependent on location. Compared to hand relaxed, pressuresduring 25% MGF, 50% MGF, and MGF were significantly greater at HH(p<0.05). Pressures during both 50% MGF and MGF were significantlygreater than hand relaxed at ⅓ DWC-HH Proximal (p<0.05). At ¾ DWC-HHDistal, only the pressures during MGF were significantly greater thanhand relaxed (p<0.0001). At all five locations, the pressures during 50%MGF were not significantly different than during 25% MGF (p>0.05).However, as the grip force increased to MGF, pressures weresignificantly greater than those during both 25% and 50% MGF at HH(p<0.05). In addition, MGF resulted in significantly greater pressuresthan 25% MGF at both ⅓ DWC-HH Proximal and ¾ DWC-HH Distal (p<0.05).Again, there were no significant differences between the initial andfinal pressures measured at HH during any of the hand activities (p=1).

Intracarpal tunnel pressure measured during application of an externalforce applied to the patient's palm using the grip dynamometer (n=7) wasless than the pressure measured during the same force level with thepatient actively gripping the same grip dynamometer. Mean intracarpaltunnel pressure (±1 SE) during application of an external force of 25%MGF, 50% MGF, and MGF were 47% (±11%), 49% (±10%), and 49% (±8%),respectively, of the mean pressures measured with the same force levelswhile the patient was actively gripping.

FIG. 20 compares mean intracarpal tunnel pressures adjacent HH beforeand after release of the transverse carpal ligament. For all six handactivities, the pressures after ligament division were significantlyless than those before (p<0.05).

In summary, intracarpal tunnel pressures were measured in patients withCTS to better understand the magnitude and variability duringquantifiable hand activities. Finger flexion, pinch, and grip activitiesall caused increases in pressure when compared to the relaxed hand.Pressures during each hand activity, as well as relaxed, variedsignificantly depending on location within the carpal tunnel, with themaximum pressure always occurring adjacent the hook of the hamate.Pressures measured adjacent the hook of the hamate after division of thetransverse carpal ligament were significantly lower than those measuredbefore ligament release for the same hand activities.

In this study, the mean peak intracarpal tunnel pressure measured in therelaxed hand of patients with CTS, 56 mm Hg (range: 10-104 mm Hg), wascomparable with those previously reported. However, intracarpal tunnelpressures measured during active hand use were substantially greaterthan those previously reported. The mean peak pressure recorded duringMGF was 1151 mm Hg (range: 149-2500 mm Hg). Peak pressures reported byothers reached only 319 mm Hg during active power grip. In previousstudies, active power grip consisted of a clenched fist without graspingan object. Consequently, active hand use was neither controlled norquantified. In this study, intracarpal tunnel pressures were recorded inan active hand where the magnitude of the force generated during handactivity was both controlled and quantified.

Several possibilities exist for why intracarpal tunnel pressures of themagnitude observed in this study have not been reported previously.Since pressure is dependent on how forcefully the hand is used and noprevious studies measuring pressure during hand use reported the forcegenerated during hand use, one possibility is that patients in thisstudy used their hands more forcefully than those previously. Forexample, FIG. 19 shows that the mean pressure at HH decreased by 38% and57% when the grip force was reduced by 50% and 75%, respectively. Toensure that the hand activities were performed accurately by patients inthis study, each patient practiced both grip and pinch activitiespreoperatively, received minimal or no sedation during performance ofthe hand activities at the time of surgery, and received specificinstructions along with visual feedback of their force levels duringperformance of the hand activities.

A second possibility is that because pressure varies withproximal-distal location within the carpal tunnel, previous studies didnot measure the pressure at the location where the peak occurred duringactive grip. As an example, FIG. 19 shows that if the pressure duringMGF were measured 0.6 cm proximal to the center of the hook of thehamate, a 45% reduction in the mean peak pressure occurs. Only oneprevious study measured pressures from proximal-to-distal within thecarpal tunnel in combination with active hand use. However, theproximal-distal locations of the pressure measurements relative to thehook of the hamate, where we recorded the peak pressure, are unknown. Inaddition, because the magnitude of the grip force was not reported, itis unknown whether its variation may have affected the location wherepeak pressure was recorded.

Both the type of transducer used for pressure measurement and itscalibration range are a third possibility that may have affectedprevious pressure recordings. In this study, a miniature pressuretransducer enclosed in a catheter was placed directly within the carpaltunnel. This type transducer is capable of measuring both hydrostaticand contact pressures combined. All but one of the previous studiesreporting pressures during active hand use relied on fluid-filledcatheters that measure hydrostatic pressure only. The single study usinga catheter-tip based pressure transducer, however, did not quantify thegrip force used during pressure measurement.

Initially, the measurement range of the transducer used in this studywas inadequate to measure the peak pressures that occurred. Themeasurement range was increased four times before reaching a final upperlimit of 3000 mm Hg that was capable of recording the peak pressures.Only one previous study reported the range of their pressure measurementsystem. In that study, the maximum pressure measured equaled the limitof the measurement system range, 250 mm Hg. Therefore, it is unknownwhether greater pressures occurred.

A fourth possibility is that placement of the pressure transducerrelative to both the contents of the carpal tunnel and the flexorretinaculum may affect the pressure measured. In this study, thetransducer was inserted from proximal to distal in the carpal tunnelbetween the contents of the carpal tunnel (tendons, nerve, synovium) andthe deep surface of the transverse carpal ligament (TCL). During activefinger flexion, the contents of the carpal tunnel shift, causingcompression of the median nerve against the TCL by the tensed flexortendons. Contact between the contents of the carpal tunnel and the deepsurface of the TCL also is evident from the volar migration of thecontents that exists following carpal tunnel release. By placing thetransducer in this location, it was believed that the maximum contactpressures could be measured between the compliant contents and the morerigid TCL.

While previous research has shown that intracarpal tunnel pressurevaries from proximal to distal in patients with CTS, there is a lack ofagreement on both how this pressure is distributed and where the maximumpressure occurs. With the wrist in neutral, two different pressuredistribution trends were reported. In the first, pressure increased fromproximal to distal reaching a maximum at either 1 cm or 3 cm distal tothe distal wrist crease and then decreased distally in both relaxed andgripping hands. In the second, pressure variations occurred fromproximal to distal reaching a maximum at 4 cm distal to the distal wristcrease in the relaxed hand.

In this study, the pressure distribution trend was similar to the first,increasing from proximal to distal, reaching a maximum, and decreasingdistally in both relaxed and active hands. In this study, maximumpressure consistently occurred adjacent the hook of the hamate at a meandistance of 2.0 cm (range: 1.6-2.3 cm) distal to DWC. Because pressuremeasurements in this study, as well as the others, were obtained atdiscrete locations, it is not possible to identify the location of theabsolute maximum pressure. However, it is evident that a pressureprofile that varies as a function of proximal-to-distal position existswhether the hand is passive or active.

In this study, peak intracarpal tunnel pressure coincided with alocation adjacent the hook of the hamate. In previous studies thatreported pressures at various proximal-to-distal locations in the carpaltunnel, the relationship between the peak pressure and its locationrelative to the hook of the hamate was not reported. Pressures weremeasured at fixed distances relative to either the distal wrist creaseor the skin incision where the pressure transducer was inserted.Consequently, no information was provided regarding the location of thepressure measurement relative to the hook of the hamate.

Unlike previous studies that measured pressures at fixed distancesrelative to an external landmark, we chose to standardize themeasurement locations based on each patient's hand size. Theproximal-to-distal distance from the center of the hook of the hamate tothe proximal pisiform was chosen as the reference measurement from whichstandardized locations for pressure measurement were obtained. Pressuremeasurements at these standardized locations were referenced to aninitial pressure measurement located adjacent the center of the hook ofthe hamate.

While no previous studies correlated the location of peak intracarpaltunnel pressure with proximity to the hook of the hamate, maximumpressure adjacent the hook of the hamate seems reasonable based on theanatomic configuration of the carpal tunnel. The TCL is defined by itsbony attachments to the pisiform, hook of the hamate, tuberosity of thescaphoid, and ridge of the trapezium, making it the stiffest segment ofthe flexor retinaculum. In this study, pressure was measured using atransducer that measured both hydrostatic and contact pressure combined.The transducer was located between the carpal tunnel contents and thedeep side of the TCL. Because the TCL provides significant restraintagainst movement of the contents of the carpal tunnel, contact pressurewould be greater where the ligament is stiffest. Peak pressure beneaththe ligament, between its bony attachments, also correlates with thecentral point of the constricted part of the median nerve in patientswith CTS.

Most research reporting intracarpal tunnel pressures neglected thesignificance of position within the carpal tunnel where pressure wasmeasured. The dynamic behavior of intracarpal tunnel pressure results insignificantly different pressures with minor changes inproximal-to-distal position. As shown in FIGS. 18 and 19, thesedifferences become more significant as the hand activity becomes moreforceful. Because intracarpal tunnel pressure is a function ofproximal-to-distal position within the carpal tunnel, any pressuresreported should identify the location where the measurement is taken.

Complete division of the TCL resulted in significantly lower pressuresadjacent the hook of the hamate, for all hand activities (FIG. 20).Although the mean intracarpal tunnel pressures for the active handbefore ligament division were substantially greater than those reportedpreviously, the mean pressures after ligament division for both therelaxed and active hands were comparable with those previously reported.This significant reduction in intracarpal tunnel pressure validates thatconsiderable contact pressures exist against the deep surface of the TCLprior to its release.

Much of the research on intracarpal tunnel pressure includesinvestigation of the effect of wrist position on pressure. Onelimitation of this study was that wrist position was not measured.Although each patient was both instructed to maintain a neutral wristposition during active hand use and practiced each activitypreoperatively while maintaining a neutral wrist position, nomeasurement of wrist position was recorded. While slight variations inwrist position between patients may have affected individual pressures,the intracarpal tunnel pressures reported reflect the natural wristposition for each patient during each hand activity.

Another limitation of this study was the number of patients included ineach hand activity. Because of variations in the pressure measurementprotocol, not all patients were included in each hand activity at eachproximal-to-distal location. While a larger patient population mayaffect the significance level between the different proximal-to-distalmeasurement locations and the different hand activities, the generalobservations reported in this study should remain valid.

While an increase in resting intracarpal tunnel pressure beyond athreshold of 30 mm Hg has been accepted as a primary contributor inpatients with CTS, the role of dynamic pressures associated with activehand use remains less apparent. Although increases in intracarpal tunnelpressure during active hand use have been suggested as a possiblecontributor to CTS, there may be other advantageous functions of thesedynamic pressures. The pressures observed in this study provideadditional information enabling a new theory regarding the role ofdynamic intracarpal tunnel pressures in the etiology of CTS.

Alterations in the mechanical properties of the TCL in patients with CTShave been suggested as a potential factor in the etiology of CTS. Inaddition, the presence of myofibroblasts in the TCL of patients with CTSsuggests that the ligament may be undergoing constant contraction.Others have suggested that the TCL requires regular tensile force tomaintain its length and reduce the signs and symptoms of CTS. Theseobservations suggest that morphologic alterations of the TCL may resultfrom an absence of sufficient tensile stress causing it to contract.Consequently, a force imbalance may exist and play a role in theetiology of CTS.

If the TCL requires regular tensile stress to maintain its elasticproperties and resist contraction, then dynamic pressures, such as thoseobserved in this study, that occur during forceful hand use may benecessary on a regular basis to provide the tensile stress that the TCLneeds. Without this regular stress, the TCL may shorten and become lesscompliant. A less compliant ligament may reduce the allowable volumethat the contents of the carpal tunnel need, thereby increasing theresting pressure. To maintain a balance of forces between the contentsof the carpal tunnel attempting to preserve tunnel volume and the TCLtrying to contract, a mechanism for the application of this requiredstress in the TCL must exist. One possibility for increasing stress inthe TCL by periodically increasing intracarpal tunnel pressure involvesthe lumbrical muscles.

The lumbrical muscles migrate proximally into the carpal tunnel duringfinger flexion and increase pressure in the carpal tunnel. However,finger flexion alone may not be sufficient to produce the tensile stressrequired for the TCL to maintain its desired morphology. Forceful handuse combined with finger flexion that delivers the lumbrical musclesbeneath the TCL with active contraction may be required to adequatelystress the TCL, enabling it to maintain its elastic properties. In thisstudy, only when hands were used forcefully were the intracarpal tunnelpressures at their peak. When patient's hands were in a relaxed positionwith fingers extended and a force applied to the palm of their hand bythe physician with the grip dynamometer, intracarpal tunnel pressureswere approximately one-half what they were when the patient activelygripped the dynamometer using the same force. Although the datapresented in this study has been used to propose this new theory,further investigation is required to better understand the role of forceimbalance in the etiology of CTS.

As can be seen, therefore, the present invention includes the followinginventive embodiments among others:

1. A method for treating a patient with carpal tunnel syndrome,comprising: identifying a location of the patient's flexor retinaculumsuitable for treatment; and injecting an agent into said location of theflexor retinaculum in one or more doses sufficient to weaken thestructural integrity of the flexor retinaculum.

2. A method as recited in embodiment 1, wherein the agent comprises oneor more doses of collagenase.

3. A method as recited in embodiment 2, wherein the agent comprises acorticosteroid.

4. A method as recited in embodiment 1, wherein identifying a suitabletreatment location of the patient's flexor retinaculum comprises:positioning an imaging detector adjacent a region of the patient's hand;the region being associated with the flexor retinaculum, and generatingan image of the patient's hand.

5. A method as recited in embodiment 1, wherein the flexor retinaculumincludes the transverse carpal ligament.

6. A method as recited in embodiment 1, wherein the flexor retinaculumincludes its attachment to the bones.

7. A method as recited in embodiment 4, wherein generating an imagecomprises positioning an ultrasound transducer adjacent the patient'shand and generating an ultrasound image.

8. A method as recited in embodiment 1, further comprising: increasingthe tensile stress in the flexor retinaculum subsequent to injectingsaid agent.

9. A method as recited in embodiment 8, wherein the increase in tensilestress is generated by pressure within the carpal tunnel, said pressuregenerated by one or more of the following: having the patient use one ormore digits of the hand, having the patient grip the hand around anobject; flexing one or more fingers into the palm of the hand and havingthe patient pinch a thumb and one or more fingers of the hand together.

10. A method as recited in embodiment 9, wherein the object comprises adynamometer.

11. A method as recited in embodiment 9, wherein the object is pressedinto the palm or heel of the patient's hand.

12. A method as recited in embodiment 1, further comprising: measuringpressure within the carpal tunnel

13. A method as recited in embodiment 1, further comprising cutting theflexor retinaculum with a blade.

14. A method as recited in embodiment 4: wherein identifying a suitabletreatment location of the patient's flexor retinaculum further comprisescomputing the palmer-to-dorsal depth from the palm of the hand to theflexor retinaculum; and wherein the agent is injected via a needle atsaid computed palmer-to-dorsal depth along an axis substantiallyparallel to an imaging surface of the detector.

15. A method as recited in embodiment 1: wherein identifying a suitabletreatment location of the patient's flexor retinaculum further comprisescomputing the palmer-to-dorsal depth from the palm of the hand to theflexor retinaculum; and wherein the agent is injected via a needle atsaid computed palmer-to-dorsal depth along an axis substantiallyparallel to a longitudinal axis of the flexor retinaculum.

16. A method as recited in embodiment 1, wherein the agent is deliveredat a central portion of the flexor retinaculum.

17. A method as recited in embodiment 1, further comprising: inserting aguide tube into the hand adjacent the flexor retinaculum; and accessingthe flexor retinaculum at the distal end of the guide tube.

18. A method as recited in embodiment 17, further comprising: advancinga pressure sensor within said guide tube to said treatment location; andmeasuring the pressure at said location.

19. A method as recited in embodiment 17, further comprising: advancinga cutting probe within said guide tube to said treatment location; andcutting tissue associated with the flexor retinaculum.

20. A system for treating a patient with carpal tunnel syndrome,comprising: a needle guide; an injection needle; the needle guidecomprising a guide hole configured for receiving the injection needle;and an agent configured for delivery within said injection needle to atissue region associated with the flexor retinaculum of the patient;wherein said agent is configured to weaken the structural integrity ofthe flexor retinaculum.

21. A system as recited in embodiment 20, further comprising: a clampcoupled to the needle guide; wherein the clamp comprises a referencesurface for positioning at a palm of the patient's hand; wherein theneedle guide is slideably coupled to the clamp such that the needleguide may be adjusted with respect to the reference surface.

22. A system as recited in embodiment 21, wherein the longitudinal axisof the guide hole is substantially parallel to the reference surface.

23. A system as recited in embodiment 21, further comprising an imagingdevice configured for imaging the carpal tunnel during injection;wherein the clamp is configured to house the imaging device.

24. A system as recited in embodiment 23, wherein the imaging device ispivotably coupled to the clamp to allow for transverse and longitudinalimages of the carpal tunnel to be obtained.

25. A system as recited in embodiment 23, wherein the imaging devicecomprises an imaging surface; wherein the imaging surface issubstantially parallel to the longitudinal axis of the guide hole of theneedle guide.

26. A system as recited in embodiment 25, wherein the needle guide isconfigured to be adjusted in a palmar-dorsal direction while thelongitudinal axis of the guide hole remains substantially parallel tothe imaging surface.

27. A system as recited in embodiment 21, wherein the clamp and needleguide comprise an indicator configured to indicate a depth of needleinsertion with respect to the reference surface.

28. A system as recited in embodiment 20, further comprising: a guidetube disposed within the guide hole; the guide tube configured to beinserted into the hand adjacent the flexor retinaculum; wherein theguide tube comprises a central channel sized to accommodate delivery ofan instrument to the tissue region.

29. A system as recited in embodiment 28, further comprising: a pressuresensor sized to be received within said guide tube to be delivered tothe tissue region; wherein the pressure sensor is configured tomeasuring the pressure at said location.

30. A system as recited in embodiment 28, further comprising: a cuttingprobe sized to be received within said guide tube to be delivered to thetissue region; and the cutting probe configured to cut tissue associatedwith the flexor retinaculum.

31. A system as recited in embodiment 21, further comprising: a linkageattached to the clamp; wherein the linkage is configured to couple tothe patients hand; wherein the linkage comprises a first joint thatallows rotation of the clamp with respect to the hand.

32. A system as recited in embodiment 31, wherein the first joint isconfigured to allow rotation of the clamp in a flexion-extensiondirection with respect to the patient's hand.

33. A system as recited in embodiment 32, the linkage furthercomprising: a second joint; wherein the second joint is configured toallow rotation of the clamp in a radial-ulnar direction with respect tothe patient's hand.

34. A system as recited in embodiment 31, wherein the linkage isconfigured to allow proximal to distal translation of the of the clampwith respect to the patient's hand.

35. A system as recited in embodiment 33, the linkage furthercomprising: a third joint; wherein the third joint is configured toallow rotation of the clamp in a internal-external direction withrespect to the patient's hand.

36. An apparatus for treating a patient with carpal tunnel syndrome,comprising: a needle guide; an injection needle; the needle guidecomprising a guide hole configured for receiving the injection needle;and a clamp coupled to the needle guide; wherein the clamp comprises areference surface for positioning at a palm of the patient's hand;wherein the needle guide is slideably coupled to the clamp such that theneedle guide may be adjusted with respect to the reference surface.

37. An apparatus as recited in embodiment 36, further comprising: animaging device configured for imaging the carpal tunnel duringinjection; wherein the clamp is configured to house the imaging device

38. An apparatus as recited in embodiment 36, further comprising: anagent configured for delivery within said injection needle to a tissueregion associated with the flexor retinaculum of the patient; whereinsaid agent is configured to weaken the structural integrity of theflexor retinaculum.

39. An apparatus as recited in embodiment 36, wherein the longitudinalaxis of the guide hole is substantially parallel to the referencesurface.

40. An apparatus as recited in embodiment 36, wherein the imaging deviceis pivotably coupled to the clamp to allow for transverse andlongitudinal images of the carpal tunnel to be obtained.

41. An apparatus as recited in embodiment 37, wherein the imaging devicecomprises an ultrasound transducer having an imaging surface; whereinthe imaging surface is substantially parallel to the guide hole of theneedle guide.

42. An apparatus as recited in embodiment 36, wherein the needle guideis configured to be adjusted in a palmar-dorsal direction while thelongitudinal axis of the guide hole remains substantially parallel tothe reference surface.

43. An apparatus as recited in embodiment 36, wherein the clamp andneedle guide comprise an indicator configured to indicate a depth ofneedle insertion with respect to the reference surface.

44. An apparatus as recited in embodiment 36, further comprising: aguide tube disposed within the guide hole; the guide tube configured tobe inserted into the hand adjacent the flexor retinaculum; wherein theguide tube comprises a central channel sized to accommodate delivery ofan instrument to the tissue region.

45. An apparatus as recited in embodiment 44, further comprising: apressure sensor sized to be received within said guide tube to bedelivered to the tissue region; wherein the pressure sensor isconfigured to measuring the pressure at said location.

46. An apparatus as recited in embodiment 44, further comprising: acutting probe sized to be received within said guide tube to bedelivered to the tissue region; wherein the cutting probe is configuredto cut tissue associated with the flexor retinaculum.

47. An apparatus as recited in embodiment 36, further comprising: alinkage attached to the clamp; wherein the linkage is configured tocouple to the patients hand; wherein the linkage comprises first andsecond joints that allow rotation of the clamp with respect to the hand;wherein the first joint is configured to allow rotation of the clamp ina flexion-extension direction with respect to the patient's hand; andwherein the second joint is configured to allow rotation of the clamp ina radial-ulnar direction with respect to the patient's hand.

48. An apparatus for treating a patient with carpal tunnel syndrome,comprising: a base configured to support a patient's forearm and hand;the base comprising a first surface configured to support the forearmand a second surface configured to support the hand; wherein the secondsurface is adjacent to the first surface and disposed at an angle withthe first surface; and a pivotable arm coupled to the base; wherein thepivotable arm is configured to support a needle guide.

49. An apparatus as recited in embodiment 49, the needle guidecomprising a guide hole configured for receiving an injection needle.

50. An apparatus as recited in embodiment 48, further comprising: aclamp coupling the pivotable arm and the needle guide; wherein theneedle guide is slideably coupled to the clamp such that the needleguide may be adjusted with respect to the second surface.

51. An apparatus as recited in embodiment 49, further comprising: anagent configured for delivery within said injection needle to a tissueregion associated with the flexor retinaculum of the patient; whereinsaid agent is configured to weaken the structural integrity of theflexor retinaculum.

52. An apparatus as recited in embodiment 50, further comprising: animaging device configured for imaging the carpal tunnel duringinjection; wherein the clamp is configured to house the imaging device.

53. An apparatus as recited in embodiment 49, wherein the pivotable armis configured to allow positioning of the longitudinal axis of the guidehole to be substantially parallel to the longitudinal axis of the flexorretinaculum when the hand is supported on said second surface.

54. An apparatus as recited in embodiment 48, wherein the needle guideis configured to be adjusted in a palmar-dorsal direction while thelongitudinal axis of the guide hole remains substantially parallel tothe second surface.

55. An apparatus as recited in embodiment 50, wherein the clamp andneedle guide comprise an indicator configured to indicate a depth ofneedle insertion with respect to the reference surface.

56. An apparatus as recited in embodiment 48, wherein the pivotable armallows translation and rotation of the needle guide with respect to thesecond surface.

57. An apparatus as recited in embodiment 56, wherein the pivotable armcomprises a first joint that allows rotation of the clamp in aflexion-extension direction with respect to the second surface.

58. An apparatus as recited in embodiment 57, the pivotable arm furthercomprising: a second joint; wherein the second joint is configured toallow rotation of the clamp in a radial-ulnar direction with respect tothe second surface.

59. An apparatus as recited in embodiment 57, wherein the pivotable armis configured to allow proximal to distal translation of the of theclamp with respect to the second surface.

60. An apparatus as recited in embodiment 58, the pivotable arm furthercomprising: a third joint; wherein the third joint is configured toallow rotation of the clamp in a internal-external direction withrespect to the second surface.

61. A method for treating a patient with carpal tunnel syndrome,comprising: identifying a location of the patient's flexor retinaculumsuitable for treatment; and cutting at least a portion of the flexorretinaculum.

62. A method for treating a patient with carpal tunnel syndrome,comprising: identifying a location of the patient's carpal tunnelsuitable for treatment; and delivering an agent into the carpal tunnelsynovium of the patient.

Although the description above contains many details, these should notbe construed as limiting the scope of the invention but as merelyproviding illustrations of some of the presently preferred embodimentsof this invention. Therefore, it will be appreciated that the scope ofthe present invention fully encompasses other embodiments which maybecome obvious to those skilled in the art, and that the scope of thepresent invention is accordingly to be limited by nothing other than theappended claims, in which reference to an element in the singular is notintended to mean “one and only one” unless explicitly so stated, butrather “one or more.” All structural, chemical, and functionalequivalents to the elements of the above-described preferred embodimentthat are known to those of ordinary skill in the art are expresslyincorporated herein by reference and are intended to be encompassed bythe present claims. Moreover, it is not necessary for a device or methodto address each and every problem sought to be solved by the presentinvention, for it to be encompassed by the present claims. Furthermore,no element, component, or method step in the present disclosure isintended to be dedicated to the public regardless of whether theelement, component, or method step is explicitly recited in the claims.No claim element herein is to be construed under the provisions of 35U.S.C. 112, sixth paragraph, unless the element is expressly recitedusing the phrase “means for.”

What is claimed is:
 1. A system for treating a patient's hand,comprising: a needle guide; an injection needle; the needle guidecomprising a guide hole configured for receiving the injection needle; aclamp coupled to the needle guide; wherein the clamp comprises areference surface for positioning at a palm of the patient's hand;wherein the needle guide is slideably coupled to the clamp such that theneedle guide may be adjusted with respect to the reference surface; animaging device configured for real-time imaging the flexor retinaculumwith respect to surrounding tissue during injection; wherein the clampis configured to house the imaging device; wherein the imaging devicecomprises an imaging surface; wherein the imaging surface issubstantially parallel to a longitudinal axis of the guide hole of theneedle guide; and an agent configured for delivery within said injectionneedle to a tissue region associated with the flexor retinaculum of thepatient.
 2. A system as recited in claim 1, wherein a longitudinal axisof the guide hole is substantially parallel to the reference surface. 3.A system as recited in claim 1, wherein the imaging device is pivotablyattached to the clamp to allow for the imaging device to be orientedwith respect to the clamp to obtain transverse and longitudinal imagesof the flexor retinaculum.
 4. A system as recited in claim 1, whereinthe needle guide is configured to be adjusted in a palmar-dorsaldirection while the longitudinal axis of the guide hole remainssubstantially parallel to the imaging surface.
 5. A system as recited inclaim 1, wherein the clamp and needle guide comprise an indicatorconfigured to indicate a depth of needle insertion with respect to thereference surface.
 6. A system as recited in claim 1, furthercomprising: a guide tube disposed within the guide hole; the guide tubeconfigured to be inserted into the hand adjacent the flexor retinaculum;wherein the guide tube comprises a central channel sized to accommodatedelivery of an instrument to the tissue region.
 7. A system as recitedin claim 6, further comprising: a pressure sensor sized to be receivedwithin said guide tube to be delivered to the tissue region; wherein thepressure sensor is configured to measure pressure at a location in saidtissue region.
 8. A system as recited in claim 6, further comprising: acutting probe sized to be received within said guide tube to bedelivered to the tissue region; wherein the cutting probe is configuredto cut tissue associated with the flexor retinaculum.
 9. A system asrecited in claim 1, further comprising: a linkage attached to the clamp;wherein the linkage is configured to couple to the patient's hand; andwherein the linkage comprises a first joint that allows rotation of theclamp with respect to the hand.
 10. A system as recited in claim 9,wherein the clamp is configured to rotate about the first joint in apalmar-dorsal direction with respect to the patient's hand.
 11. A systemas recited in claim 10, the linkage further comprising: a second jointoriented perpendicular to the first joint; wherein the clamp isconfigured to rotate about the second joint in a radial-ulnar directionwith respect to the patient's hand.
 12. A system as recited in claim 11,the linkage further comprising: a third joint; wherein the clamp isconfigured to rotate about the third joint in an internal-externaldirection with respect to the patient's hand.
 13. A system as recited inclaim 9, wherein the linkage is configured to allow proximal to distaltranslation of the clamp with respect to the patient's hand.
 14. Asystem as recited in claim 1, wherein said agent is formulated to weakenthe structural integrity of the flexor retinaculum.
 15. A system fortreating a patient's hand, comprising: a needle guide; an injectionneedle; the needle guide comprising a guide hole configured forreceiving the injection needle; a clamp coupled to the needle guide;wherein the clamp comprises a reference surface for positioning at apalm of the patient's hand; wherein the needle guide is slideablycoupled to the clamp such that the needle guide may be adjusted withrespect to the reference surface; a linkage attached to the clamp;wherein the linkage is configured to couple to the patient's hand; andwherein the linkage comprises a first joint that allows rotation of theclamp with respect to the hand; wherein the clamp is configured torotate about the first joint in a palmar-dorsal direction with respectto the patient's hand; and an agent configured for delivery within saidinjection needle to a tissue region associated with the flexorretinaculum of the patient.
 16. A system as recited in claim 15, whereinsaid agent is formulated to facilitate rupture of collagen fibers withinthe flexor retinaculum.
 17. A system as recited in claim 15, whereinsaid agent is formulated to facilitate lengthening of collagen fiberswithin the flexor retinaculum.
 18. A system as recited in claim 15,wherein said agent is formulated to facilitate failure of collagenfibers within the flexor retinaculum.
 19. A system as recited in claim15, wherein said agent comprises one or more doses of collagenase.
 20. Asystem as recited in claim 19, wherein said agent comprises aninjectable form of clostridium histolyticum.
 21. A system as recited inclaim 15, further comprising an imaging device configured for real-timeimaging the flexor retinaculum with respect to surrounding tissue duringinjection; wherein the clamp is configured to house the imaging device.22. A system as recited in claim 21, wherein the imaging device ispivotably attached to the clamp to allow for the imaging device to beoriented with respect to the clamp to obtain transverse and longitudinalimages of the carpal flexor retinaculum.
 23. A system as recited inclaim 21, wherein the imaging device uses ultrasound.
 24. A system asrecited in claim 15, the linkage further comprising: a second jointoriented perpendicular to the first joint; wherein the clamp isconfigured to rotate about the second joint in a radial-ulnar directionwith respect to the patient's hand.
 25. A system as recited in claim 24,the linkage further comprising: a third joint oriented perpendicular tothe first joint and second joint; wherein the clamp is configured torotate about the third joint in an internal-external direction withrespect to the patient's hand.
 26. A system as recited in claim 15,wherein the linkage is configured to allow proximal to distaltranslation of the clamp with respect to the patient's hand.
 27. Asystem as recited in claim 15, wherein said agent is formulated toweaken the structural integrity of the flexor retinaculum.